Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a first image in a sequence for a display screen or portionthereof with transitional graphical user interface showing our newdesign;

FIG. 2 is a second image thereof; and,

FIG. 3 is a third image thereof.

The appearance of the transitional image transitions sequentiallybetween the images shown in FIGS. 1-3. The process or period in whichone image transitions to another forms no part of the claimed design.The broken lines show a display screen or portion thereof and portionsof the graphical user interface and form no part of the claimed design.

CLAIM The ornamental design for a display screen or portion thereof withtransitional, graphical user interface, as shown and described.